First off, just got a great deal on a new trex 450 se v2 cf frame and boom assembly and then on a main rotor system. Where is the best place to buy original Align parts at a fair price? Second, when I was placing my rotor system through the main frame and then I put the main gear assembly and tightened the screw it has some vertical play it seems between the top of the main gear and the bottom of the lower bearing block. I also have an MX 450 and it does not have the same play. It's almost like there should be an additional spacer on top of the main gear.

Loosen the set screw in the main shaft collar and slide it down with light finger pressure and re-tighten the set screw using thread lock.
Almost any of the vendors that advertise on this forum are good. I've had good service from Modefo and Helihobby.
Also there should be a small spacer on top of the main gear assemble that is easy to over look.

Thanks for the quick response. I tried what you said and it still seems loose, I also swapped out my MX450 main gear and it seemed to do the same. Not sure whats up. I place my mX450 gear back in it and it was tight. Not sure what's going on. Will there be play there till i hook up the servos? All though when the servos are not hocked up on the mx450 it's tight. The spacer you spoke of is basically the auto gear center coming up through the main gear correct?